如前所述，PEP 8要求对变量、方法和函数使用lower_case_with_下划线。

我更喜欢使用lower_case_with_下划线的变量和mixedCase的方法和函数，使代码更显式和可读。因此，遵循Python的“显式优于隐式”和“可读性很重要”的禅意。

通常，要遵循语言标准库中使用的约定。

There is PEP 8, as other answers show, but PEP 8 is only the styleguide for the standard library, and it's only taken as gospel therein. One of the most frequent deviations of PEP 8 for other pieces of code is the variable naming, specifically for methods. There is no single predominate style, although considering the volume of code that uses mixedCase, if one were to make a strict census one would probably end up with a version of PEP 8 with mixedCase. There is little other deviation from PEP 8 that is quite as common.

我个人在用其他编程语言开发时使用Java的命名约定，因为它是一致的，易于遵循。这样我就不会一直纠结于使用什么约定，而这本来不应该是我项目中最难的部分!

有一篇关于这方面的论文:http://www.cs.kent.edu/~jmaletic/papers/ICPC2010-CamelCaseUnderScoreClouds.pdf

它说snake_case比camelCase可读性更好。这就是为什么现代语言在任何可能的地方都使用(或应该使用)蛇。

无论是否在课堂上或在课堂外:

变量和函数小写，如下所示:

name = "John"

def display(name):
    print("John")

如果它们多于一个单词，则用下划线“_”分隔，如下所示:

first_name = "John"

def display_first_name(first_name):
    print(first_name)

并且，如果一个变量是一个常量，它是大写的，如下所示:

FIRST_NAME = "John"